In cylinder locks of conventional design, a cylindrical key-receiving plug having a first series of radially disposed channels is rotatably mounted within a cylindrical bore in a housing having a second matching series of channels known as "pin chambers". The pin chambers are in coaxial alignment with the first series of channels and open upon the bore. The opposite extremities of the pin chambers, furthest from the bore, are closed. Each pin chamber is adapted to confine a coil spring in abutment with the closed extremity, and a bottom pin that is urged toward the key-receiving plug by the spring. In some cases, one or more top pins, control pins or master pins may be positioned between the spring and the bottom pin within the pin chamber. The combination of pin lengths determines a code for opening the lock.
In certain types of cylinder locks, generally referred to as interchangeable core locks, the portion of the housing that contains the plug and pin chambers is part of an assembly known as a "core" that is slideably removable from the lock when released by a control key. The controlled removeability of the core is desired by institutions and others where a high turnover of employees necessitates a periodic change of locks to maintain security. Cores of several different codes may be kept by the institution, all keyed to a single control key but requiring different operating keys to open the individual locks. Changing of the locks requires a total recoding of the core to accept another key. In such a case, assembly of a new and different core is required.
The core further contains the cylindrical bore that houses the key receiving plug and the wall of the bore has a series of apertures axially aligned with the first series of channels and diametrically opposed thereto. The extremities of the pin chambers furthest from the bore are closed by means of friction fit discs or "caps" as they are commonly called. Assembly of the core requires insertion, in the proper order of bottom pins, master pins, control pins, top pins, springs and finally caps into the pin chambers. As all of these parts are very small, assembly can be a long and tedious operation. Insertion or application of the caps can be a particularly frustrating part of the operation. The caps are very small and, in addition to the obvious problem of inserting them into the similarly small pin chambers, they must be squarely and precisely aligned in order to achieve the appropriate friction fit. They must then somehow be driven into the pin chamber by striking with a hammer, mallet or the like to achieve the friction fit. Misalignment entails removal of the cap and reinsertion with the possibility of further misalignments before proper cap installation is achieved. This operation must be repeated for each pin chamber of which there are conventionally either six or seven.
Thus, a method and apparatus that would permit simplified, convenient and aligned installation of a plurality of friction fit caps into the pin chambers of a core all at one time would be highly valued by locksmiths.